1. Field of the Invention
The present invention relates to a backlight assembly having improved color mixture and heat dissipation. The present invention also relates to a liquid crystal display device having the present backlight assembly.
2. Description of the Related Art
Since a liquid crystal display (LCD) device has a variety of advantages in terms of size, weight and power consumption, it has been widely used in a variety of files such as a laptop computer field, a personal computer field, and a monitor field.
Since an LCD device is not a light emissive display, it requires a backlight assembly that emits light to a liquid crystal panel.
The backlight assembly is classified according to the disposition of a light source. A backlight assembly may thus be classified as an edge-type or a direct-type backlight assembly. The edge-type backlight assembly includes a light guide plate and a light source disposed on a side surface of the light guide plate. The light guide plate guides the light emitted from the light source frontward. The direct-type backlight assembly includes a plurality of light sources formed on a rear surface of the liquid crystal panel. The light emitted from the light sources is directly emitted to the liquid crystal panel.
As a light source for the backlight assembly, an electroluminescent (EL), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), and a light emitting diode (LED) may be used.
The backlight assembly using the CCFL may be reduced in service life due to mercury filled in the CCFL, which can be easily coupled to metal to generate an amalgam. Furthermore, the luminance variation is so high according to the variation of the temperature. Furthermore, the mercury may cause environmental pollution.
To solve the above problems of the backlight assembly using the CCFL, the LED has been widely used as a light source for the backlight assembly.
In the backlight assembly using the LED, a plurality of LEDs is disposed on a bottom case at predetermined intervals. A variety of optical sheets for diffusing and focusing light are disposed above the LEDs.
A reflective plate is disposed in the rear of the LEDs.
The LEDs that are point light sources emit white light by a combination of red, green and blue LEDs or by white LEDs.
Since the LED is a point light source, there may be a luminance difference between areas where the LEDs are disposed and areas where the LEDs are not disposed. To prevent such luminance difference, a light mixing plate for generating white light by mixing red, green and blue lights is provided above the LEDs. Alternatively, the distance between the optical sheets and the LEDs must be increased.
However, when a light mixing plate is provided, the manufacturing cost and weight of the LCD device increases. Also, when the distance between the optical sheets and the LEDs increases, the overall thickness of the LCD device increases. As will be seen from a review of the present invention, it is possible to omit a light mixing plate from the LCD device according to the present invention.
In addition, heat generated from the LEDs may cause a reduction in the service life of the LCD device.